One long standing problem with the manufacture of window or door frames from pultruded fiber reinforced resin materials has been the difficulty of forming corners which need to be mechanically fastened using corner inserts, in comparison with the major competitor of extruded vinyl where the corners can be quickly and inexpensively welded.
Typically corners for pultruded materials are formed using an injection molded corner member which has two legs one of which slides into each lineal at the corner and is fastened in place by screws inserted through the wall of the lineal into a screw receptacle in the corner member. This is a relatively slow and more expensive process which is perceived to be a significant disadvantage relative to vinyl.
It is known to provide a corner insert which is held in place by injecting a sealant along the legs of the corner insert which attach the insert to the lineal. However this injection is itself problematic so that the practice has not been adopted widely.
In Canadian Patent Application 2,461,802 published 10th Jan. 2005 by Pella Corporation is disclosed a method in which a sealant is injected through an opening into the areas of the legs of the corner member. Screws are used to hold the corner member in place while the sealant cures.
In U.S. Pat. No. 4,651,482 (Borys) issued Mar. 24th 1987 and U.S. Pat. No. 4,145,150 (Rafeld) issued Mar. 20th 1979 are disclosed a similar arrangement where legs of the corner member form cavities inside the lineals which are filled by an injected sealant.